Sound should play onMouseDown, not onClick / onMouseUp

[Desmond Sadler]

To more accurately mimic real instruments, the sound should play when you initiate the action, rather than when the user is finishing the 'click'

Presumably we can just change the event to onMouseDown.

[Srgy Surkv]

Use any event that you like.
WebAudioFont is library for music not UI events.